package org.linlinjava.litemall.web.util;

/**
 * @author ：stephen
 * @date ：Created in 2019/12/17 18:40
 * @description：经纬度计算距离util
 */
public class LocationUtils {
    private static double EARTH_RADIUS = 6378.137;

    private static double rad(double d) {
        return d * Math.PI / 180.0;
    }

        /**
      * 通过经纬度获取距离(单位：米)
      *
      * @param lat1
      * @param lng1
      * @param lat2
      * @param lng2
      * @return 距离
      */
    public static Double getDistance(double lat1, double lng1, double lat2,double lng2) {
        double radLat1 = rad(lat1);
        double radLat2 = rad(lat2);
        double a = radLat1 - radLat2;
        double b = rad(lng1) - rad(lng2);
        double s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a / 2), 2)
                + Math.cos(radLat1) * Math.cos(radLat2)
                * Math.pow(Math.sin(b / 2), 2)));
            s = s * EARTH_RADIUS;
            s = Math.round(s * 10000d) / 10000d;
            s = s * 1000;
        return s;
    }

}
